Brain Tour : Our Brain : Looking at the Cerebrum :

Sometimes the behavior of a patient with brain damage give insights into the mind's workings.

When the frontal lobe is damaged...

Prefrontal lobe damaged (that's the part close to the front of the brain ) alters the person's ability to execute plans and can make them very unpleasant people to be with. This type of damage can also make them less easily irritable. The frontal lobe plays a part in emotions, mood and general behavior.
Frontal lobe damage affects movement since this area contains the the part which initiates movement and the part which carries it out.
Patients with lesions in Broca's area can sometimes speak but the speech is labored and halting. Ask them about where his family members are and this is the reply : "To bed gone and... now no ...can people ....good" . This region controls grammar and vocalisation.

When the parietal lobe is damaged...

Damage to the parietal lobe of the cortex interferes with perception of touch and pain, as well as some visual functions and the knowledge of where the body is in space. Stroke patients whose posterior ( back ) parietal lesions can have bizarre effects, one of which is referred to as "neglect". When the left posterior parietal lobe is damaged, "right neglect" occurs. This means that the poor guy treats the entire right side of his body and the word as if its not even there. This is because each side of this region of the brain integrates inputs from the different senses to form a coherent picture of what is happening in the opposite side of the body, where the signals originate.

When the temporal lobe is damaged...

Peoplw with damage to Wernicke's region, an areal in the left temporal lobe, can speak fluently but make no sense. A typical reply to a question about where his family members are might run : " Oh yes, we have been there, could be the lightbulb, but moreover it is. Have some success so it still is gone" The area deals with sense and comprehension of language.
The right temporal lobe is involved in controlling spatial task, and damage to a part of it can make someone unable to recognize faces, even those of his family members. A business man with this damage may recognize his office but may not remember the faces of his colleagues. Damage to other parts of the temporal lobes can result in dramatic hallucinations or lost of memory of past events.

When the occipital lobe is damaged...

Damage to some parts of the occipital lobe would make someone unable to acknowledge that he or she can see an object, even though he is looking straight at it. Damage to other parts of this lobe would cause some odd symptoms. For instance, following a stroke there, a patient might see the world only as a series of static images. This region deals with the sense of vision. It processes "raw" incoming signals from the retina and handles color, motion and form, and bring the visual world toward conscious perception.